The present disclosure generally relates to substrate processing, and more particularly, to methods and devices for positioning and bonding elements to substrate.
Manufacture of certain wafer-based devices often requires placing a component (e.g., a sphere) into an opening (e.g., a hole) in a substrate at a specified position. For example, an integrated optical device can include a lens, a conductor layer, and other components formed in a substrate. Such a device can be manufactured by fabricating multiple devices on a single substrate through multiple steps of wafer processing and then dicing the processed substrate into separate devices.
More specifically, one type of an optical head for an optical data storage system requires formation of a solid immersion lens having a spherical surface and a flat surface in a slider. See, U.S. patent application Ser. No. 08/641,513 filed on May 1, 1996 (now U.S. Pat. No. 5,881,042), Ser. No. 08/657,145 filed on Jun. 3, 1996, and Ser. No. 08/846,916 filed on Apr. 29, 1997. The dimensions of the solid immersion lens (e.g., the spacing between the spherical surface and the flat surface) and the position of the lens in the slider may significantly affect the optical performance and other properties of the resultant optical head. Hence, it is desirable to develop processing techniques and respective tools to precisely control the device parameters during the fabrication process.
The devices and techniques of this disclosure allow for accurately placing elements, e.g., spheres, into the holes of a substrate in a batch process. One embodiment of the device includes a reference plate having a flat surface as a reference surface, a plurality of spacer balls disposed on the reference surface, a first weight plate, and a second weight plate. The spacer balls support a substrate to be processed and to define a spacing between the reference surface and the substrate. The first weight plate includes protruded contacts which extend into holes in the substrate to press elements respectively placed in the holes against the reference surface, without applying pressure on the substrate. The second weight plate is disposed above the reference plate to press the substrate against the spacer balls.
A positioning cage may be placed above the reference surface and below the substrate to define the positions of the elements. One embodiment of the positioning cage has two arrays of holes. The first array of positioning holes are smaller than the elements and respectively hold the elements in the positioning holes to contact the reference surface. The second array of spacer-ball holes have a diameter greater than that of the spacer balls so that the spacer balls can be placed in these holes. A plurality of supporting elements are disposed on the reference surface to support a rim of each spacer-ball hole. Each supporting element has a height less than the diameter of the spacer balls.
These and other aspects and associated advantages will become more apparent in light of the following detailed description, the accompanying drawings, and the appended claims.